LONDON/ANCHORAGE - BP reported yet another pipeline leak at its Alaskan oilfields, frustrating the oil giant's attempts to rebuild its reputation after the Gulf of Mexico oil spill.
BP said on Monday that a pipeline at its 30,000 barrel per day Lisburne field, which is currently closed for maintenance, ruptured during testing and spilled a mixture of methanol and oily water onto the tundra.
The London-based company has a long history of oil spills at its Alaskan pipelines - accidents which have hurt its public image in the U.S., where around 40 percent of its assets are based.
The Alaska Department of Environmental Conservation said the spill occurred on Saturday and amounted to 2,100 to 4,200 gallons.
A BP spokesman said the cleanup was under way and the company would determine the cause "in due course."
Lisburne, which is managed as part of the Greater Prudhoe Bay Unit, has produced no oil since June 18, according to Alaska Oil and Gas Conservation Commission records, suggesting maintenance work requiring a prolonged shutdown.
The spokesman said the field had been undergoing "its annual maintenance."
BP's blown out Macondo well caused the worst offshore oil spill in U.S. history, spewing almost 5 million barrels of oil into the Gulf and putting BP's future in the U.S. at risk.
Previous problems including leaks from corroded pipelines in Alaska and the fatal Texas City refinery blast in 2005 had already earned the company a poor reputation for safety, something analysts say it needs to address if it is to continue to grow in North America.
BP shares were down 1.089 percent at 454 pence at 0919 GMT.
Production from the entire Lisburne field remains shut off while the spill is addressed, Alaska officials said.
Immediate efforts are focused on containment and cleanup, said Tom DeRuyter, state on-scene coordinator for the Department of Environmental Conservation.
The methanol-produced water mix has spread into wet tundra as well as onto a gravel pad, bringing risks to slow-growing vegetation, DeRuyter said.
"You have actively growing plants and they're very susceptible to the contaminants," he said.
The pipeline will also have to be dug up to allow for an investigation into why it failed, he said.
Resumption of normal operations at that part of the field may require a relatively long wait, DeRuyter said.
"I think they're looking at trying to get that pad back up before freeze-up," he said.
(Editing by James Jukwey and Hans-Juergen Peters)